Electrical terminal blocks with mounting rail



y 1966 A. R. NORDEN 3,253,251

ELECTRICAL TERMINAL BLOCKS WITH MOUNTING RAIL Filed April 8, 1963 2 Sheets-Sheet l prrok e 7 y 1966 A. R. NORDEN 3,253,251

ELECTRICAL TERMINAL BLOCKS WITH MOUNTING RAIL Filed April 8, 1963 2 Sheets-Sheet 2 FIG 5 g M 66 )2! M FIG. 7.

'1' n III INVENOR. ALEXA IVDER A. A OQDEN FTTORNE'Y United States Patent 3,253,251 ELECTRICAL TERMINAL BLOCKS WITH MOUNTING RAIL Alexander R. Norden, 350 Central Park W., New York, N.Y. Filed Apr. 8, 1963, Ser. No. 271,160 Claims. (Cl. 339198) The present invention relates generally to electrical connectors for separately connecting multiple pairs of wire, and in particular to terminal blocks adapted to be mounted on a mounting channel or rail.

Electrical connectors, useful as terminals, splices and taps, find widespread application in a wide variety of power supplies, controls, and diverse electrical apparatus. Such electrical connectors usually employ a screw-type clamp for establishing electrical connection to an inserted wire. The screw type clamp is usually mounted on an appropriate insulating body which may be of molded phenolic, nylon or other suitable material. There are a number of practical problems concerning such connectors which, if solved, could afford substantial economies in manufacture, and greater facility and practicality in use.

Broadly, it is an object of the present invention to provide an improved electrical connector, particularly of the type having a screw-type clamp, which exhibits economies in manufacture and has improved mechanical and electrical characteristics.

One common form of electrical connector in accordance with the prior art includes a clamping member having a tapped screw hole which receives a clamping screw. This connector serves directly, or indirectly, to provide mechanical and electrical contact to an inserted wire or lead. Such connectors are shipped in large numbers. When in transit, the incidental shaking and vibration often causes many of the screws to rotate and become completely unscrewed. The user then has the bother of reassembling the scattered screws into the clamping members. To avoid the inadvertent disengagement of the screws from the clamping members during shipment, it has been customary to drive the screws all the way into the clamping members tightly. When this practice is adopted by the manufacturer of the connector, the installer is required to back off the clamping screw before he can make an electrical connection, an operation that entails much waste of time and effort. Recognizing that connectors are used by the thousands, the foregoing considerations are of genuine practical importance.

It is a further object of the present invention to provide an electrical connector which obviates the aforesaid difiiculty. Specifically, the invention contemplates an electrical connector which may be shipped with the clamping screw thereof in any position of adjustment such that the connector is in condition for use without concern to the user over missing screws and without the necessity of first backing off the clamping screw before a wire can be inserted. Correspondingly, the manufacturer of the connector is spared the tightening operation.

In accordance with this aspect of the present invention, the clamping member in the illustrative connectors detailed below is formed of resilient sheet-metal and includes relatively movable superimposed walls formed with first and second screw holes disposed in non-concentric relation with respect to each other in the absence of a screw, when the clamping member is unstressed. Before the clamping screw can be threaded through the first and second screw holes, the clamping member is stressed to bring the holes into substantial alignment. The resilence of the clamping member and the initial non-concentric relation of the screw holes provides a binding action between the clamping screw and the clamping member which tends to preclude vibration-induced rotation of the clamping screw.

I end of the insulating body.

Consequently, the screw normally remains in any adjusted position until positively manipulated.

Electrical apparatus often requires connection means for a relatively large number of circuits. Multiple-circuit connector blocks are sometimes made with a great many side-by-side clamping screws on one piece of molded insulation. However, because the required number of circuit connections varies widely, and mixed sizes of connectors may be needed for different current ratings in any given installation, it has become a common practice to make assemblies of modular terminal blocks in a row, each block ordinarily accommodating a single circuit. A factor that limits the usefulness of such connectors is the width of the connector or terminal block measured along the length of the row of connectors. The dimension transversely of the mounting row is not normally critical. The minimum width of the connector or terminal block is physically determined by its voltage rating and by the size of terminal members which are to receive diiferent sizes of wires of various current ratings. As the physical width of the connector is cut down, there is a corresponding foreshortening of the surface leakage path between adjacent circuits and an attendant risk of insulation breakdown. It would be particularly advantageous if it were possible to accommodate a large number'of connectors per lineal foot of the row, for example, as many as 35 to 40 terminals per lineal foot, yet avoid unduly short surfacedeakage paths between adjacent circuits in the row.

Another object of the present invention is to provide an electrical connector for pairs of wires of different circuits, which realizes one or more of the aforesaid objectives. Specifically, it is within the contemplation of the present invention to provide an electrical connector which is of comparatively narrow width as measured across the current paths provided by the connector, yet which provides a comparatively long surface leakage path between metal parts identified with adjacent circuits- In accordance with this aspect of the present invention, the illustrative connector described in detail below include an elongated insulating body formedwith two pairs of cavities for containing conductor clamps. Each cavity has an entry end in the top surface of the insulating body. One of the first pair of cavities is disposed adjacent one end of the insulating body and the other of the first pair of cavities is spaced inwardly from the other A passage extends through the insulating body between the first pair of cavities to receive a connecting member. One of the second pair of cavities is spaced inwardly from said one end of the insulating body, and the other of the second pair of cavities is disposed adjacent the other end of the insulating body. A thorough passage is provided between the second pair of cavities to receive a second connecting member. First and second pairs of conductor clamps are mounted in the first and second pairs of cavities and a respective connecting member extends between the two clamps of each pair. Each of the conductor clamps is arranged to grip an inserted wire. There is a staggered relationship between the cavities which, at each end of the insulating body, provides a relatively long surface leakage path between the clamps in those cavities. The staggered relationship also minimizes the width of the connector, thereby accommodating a relatively large number of connectors along the row without sacrificing performance.

A still further problem arises out of the practice of mounting of multiple connectors or terminal blocks on a mounting rail or channel. This problem is concerned with tightening of the respective clamping screws to establish the necessary electrical connections to the inserted wires. The torque developed incident to tightening of the clamping screws usually mainfests itself in a turning or screwing of the entire connector due to the resilience of the parts and any unintended looseness that may exist between the rail and the insulating block of the connector.- In many situations, it is difficult, if not impractical, for the installer to attempt to hold the connector during the tightening of the clamping screws. Thus there is ever present the risk of damaging the parts of the insulating body that secure the connector to the mounting rail when a wire is being tightly connected.

In accordance with -a further aspect of the present invention, interengaging means is provided on the side-byside abutting surfaces of adjacent terminal blocks or connectors along the mounting rail, which interengaging means is arranged to resist the twisting torque developed due to the tightening of the respective clamping screws. The presence of such interengaging means provides a reaction force to the torque which otherwise would be allowed to manifest itself due to the resilience of the parts and any l-ooseness of fit between the respective insulating bodies or blocks and the rail.

The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred, but nonetheless illustrative, embodiments in accordance with the present invention, when taken in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a plan view of a plurality of connectors embodying features of the present invention, shown mounted in side-by-side relation on a mounting channel or rail;

FIGURE 2 is an enlarged plan view of one of the connectors shown in FIGURE 1, with said connector being adapted to connect two pairs of conductors or wires in two separate circuits;

FIGURE 3 is an enlarged left-side elevation of the connector shown in FIGURE 2;

FIGURE 4 is an end elevation of the connector shown in FIGURE 2, illustrated with the respective conductor clamps in open positions and in condition for shipping and use;

FIGURE 5 is an enlarged sectional view taken substantially along the line 55 in FIGURE 4, and looking in the direction of the arrows;

FIGURE 6 is an enlarged view taken substantially along the line 6-6 of FIGURE 5, and looking in the direction of the arrows;

FIGURE 7 is an enlarged front elevation of a resilient clamping member that is a component of the connectors in FIGURES 1-6;

FIGURE 8 is an enlarged vertical cross-section of the clamping member of FIGURE 7, assembled to a connecting member and a clamping screw, and viewed at right angles to the plane of FIGURE 6;

FIGURE 9 is a fragmentary side elevation of connector parts viewed as in FIGURE 6, but drawn to larger scale, showing at the left one clamping member and screw in an open position and showing at the right the other clamping member and screw in the clamping position for establishing an electrical connection between a wire, the right clamping member, and a conductive strap bridging the clamping members;

FIGURE 10 is a fragmentary side elevational view of a modified clamping member provided with a depending skirt which precludes accidental insertion of the wire or connector into the gap between the clamping member and the lower wall of the insulating body;

FIGURE 11 is a plan view of another form of electrical connector for establishing respective connections between pairs of wires or conductors of two circuits; and

FIGURE 12 is an exploded plan view of the metal parts of the modification shown in FIGURE 11.

Referring now specifically to the drawings, FIGURE 1 illustrates four electrical connectors 10,-12, 14 and 16 embodying features of the present invention, these connectors being mounted in side-by-side abutting relation on a segmented mounting channel or rail 18. The structure of the rail 18 is more specifically described in my copending application, Serial No. 308,126, entitled, Mounting Channel for Electrical Connectors. The electrical connectors, considered from right to left, include connector 10 designed for connecting a pair of wires of a single circuit, connectors 12 and 14 each designed for two circuits,

and connector 16 designed for three circuits. The connectors 12, 14 are of identical construction and all of the connectors incorporate certain common and related structural features. Accordingly, it will suffice for the present purposes to describe in detail the structure of one connector. Connector 14 provides a first electrical connection between the conductor C at one end thereof and the conductor C at the other end thereof in one circuit, and a second electrical connection in a second circuit between the conductor C at the one end thereof and conductor C, at the other end thereof.

In FIGURES 2 to 9, inclusive, the connector or terminal block 14 includes an insulating body 20 which is molded of nylon or other suitable insulation. The insulating body 20 has a top surface 22, opposed end walls 24, 26, side walls 28, 30 and a base wall 32. Intermediate the opposite side walls 28, 30, there is provided a longitudinally extending medial wall 34 (see FIGURES 5 and 6).

Depending from and integral with the base wall 32 are transversely extending feet 36, 38 which are symmetrically disposed about a transverse plane midway'between the ends of the insulating body 20. Feet 36, 38 are spaced inwardly from the opposite end walls 24, 26. Between feet 36, 38 there are a pair of outwardly bowed mounting formations 40, 42 which interlock with the in-turned edges of the mounting channel 18 (see FIGURE 3) and serve to secure the connector 14 on the rail 18 in a stable position. Formations 40, 42 are somewhat yielding when nylon is the insulation that is used. Webs 40a and 42a make the mounting formations stiffer; and these webs are received in regularly spaced notches 18a in the edges of the mounting channel, for holding each connector against sliding along the mounting channel.

The insulating body 20 is formed with a first pair of vertically extending cavities or guideways 44, 46 in the right longitudinal half section of the body 20 as viewed in FIGURE 2, the respective guideways 44, 46 being disposed in alignment along insulating body or block 20. Similarly, the longitudinal left-half section of the body 20 (as viewed in FIGURE 2) is formed with a second pair of cavities or guideways 48, 50 which are likewise disposed in longitudinal alignment. The guideway 44 of the first pair is disposed adjacent the end wall 24 of the body 20, while the guideway 46 of the first pair is spaced inwardly from the opposite end wall 26 of the body 20. The guideway 48 of the second pair is disposed inwardly of the guideway 44 and the adjacent end wall 24, while the guideway 50 of the second pair is disposed adjacent the end wall 26 and outwardly of the adjacent guideway 46. As seen best in FIGURES 2 and 6, the guideway 44 of the first pair is flanked or bounded at its opposite sides by the portions 28a, 34a of the side wall 28 and the medial wall 34, respectively, and at its opposite ends by the end 24 and an intermediate transverse wall 52. The guideway 46 of the first pair is bounded at its opposite side by the portion 28b of the side wall 28 and the portion 34b of the medial wall 34. At its outer end the guideway 46 is bounded by transverse wall 54 and at its inner end it is bounded by a further transverse intermediate wall 56.

The guideway 48 of the second pair is bounded at its opposite sides by the portion 30a of the side wall 30 and the portion 34c of medial wall 34. At one end, the guideway 48 is bounded by an extension of the transverse wall 52 and at its opposite end it is bounded by a further intermediate wall 58. Finally, the guideway '50 is bounded at its opposite sides or flanked by the portion 30b of the side wall 30 and the portion 34d of the medial wall 34 and at its opposite ends by the end wall 26 and the transverse intermediate wall 54.

Guideways 44, 46, 48, 50 have respective entry ends which open into the top surface 22 of the insulating body 20. At their lower ends, the respective guideways open into the two side-by-side passages 60, 62 (FIG. 4) which extend lengthwise of the insulating body in the lower half thereof (see FIGS. 5 and 6). The longitudinal passage 60 is bounded at its opposite sides by the side wall 28 and the medial wall 34, and at its bottom by the corresponding half of the base wall 32. The passage 62 is bounded on its opposite sides by the outer side wall 30 and the medial wall 34, and at its bottom by the corresponding half of the base wall 32. As seen in FIG. 6, the intermediate transverse walls 54, 58 terminate at the upper side of the respective passage 60, 62.

The passage 60 is open-ended such that wires may be inserted into the respective opposite openings 60a, 60b. Similarly, the passage 62 is open-ended such that wires may be inserted into respective wire-receiving openings 62a, 62b. As seen in FIG. 5, the respective wire-receiving openings 62a, 60b are in transverse planes at the opposite ends of the elongated insulating body 20, While the wirereceiving openings 62a, 6012 are in transverse planes spaced inwardly from the ends of the insulating block 20 and from the respective openings 60a, 62b. The wire-receiving opening 60a is separated from the wire-receiving opening 62a by the adjacent and interposed portion 34a of the medial wall 34, while the Wire-receiving opening 62b is separated from the wire-receiving opening 60b by the adjacent and interposed medial portion 34d of the medial wall 34.

Respective screw-type clamping devices 64, 66, 68 and 70 are slidably received in each of the vertically extending guideways 44, 46, 48 and 50. The clamping devices are identical in construction and accordingly it will suffice to described one in detail.

Clamping device 68 (FIGS. 6 through 9) includes a resilient clamping member which is formed of a strip of metal and includes a base wall 72a, first and second side walls 72b, 72c which project integrally and upwardly from the base wall 72a, and first and second superposed top walls 72d, 722 which are integral with and project inwardly from the respective first and second side walls 72b, 720. The top walls 72a, 72s have tapped first and second screw holes 72 72g which (FIG. 7) are disposed in non-concentric relation with respect to each other when member 72 is in its unstressed condition. In this condition, the central axes of the respective screw holes 721, 72g are spaced from each other in an amount sufiicient such that, when side walls 72b and 720 are squeezed sufiiciently to bring screw holes 72f, 72g into coaxial alignment and a clamping screw is inserted and side walls 72b and 72c are no longer squeezed, lateral forces will be developed which will cause a binding of the clamping screw 74 therein. The resilience of the clamping member 72 in the initial non-concentric nelation of the screw holes provides a binding action between the clamping screw 74 and the clamping member 72 which tends to preclude loosening of the clamping screw and maintains the same in any adjusted position, despite vibration.

As seen best in FIGS. 5 and 6, first and second conductive bridging straps 76, 78 are received in the longitudinally extending passages 60, 62, respectively. Terminal portions of bridging strap 76 extend into the respective rectangular clamping member 72 of the clamping devices 68, 70. Similarly, bridging strap- 78 extends along passages 62 and its opposite terminal portions extend into clamping devices 68, 70 (see FIG. 6). Upstanding integnal pedestals 32a, 32b on base wall 32 of the insulating body 20 support bridging strap 76, and integral upstanding pedestals 32c, 32d sup-port strap 78. The spacing between the upper ends of the respective pedestal 32a,

6 32b, 32c and 32d and the lower ends of the intermediate transverse walls 52, 54, 56 and 58 is that which provides the necessary clearance for the bridging straps 76, 78.

The respective bridging strap 76, 78 are held in position lengthwise of the passages 60, 62 by integral locking projections 78a and 78b, for example, which are received in corresponding locking recesses in the adjacent walls 34, 30 of the insulating body 20. The terminal portions of each of the bridging straps 76, 78 are formed with gripping ribs which cooperate with roughly complementary formations in the confronting base walls 72a of the clampring member 72. 'The gripping jaws are disposed in offset relation and have the tendency to form a sinuous deformation in the wire of the conductor (i.e. conductor C in FIG. 9) and to establish a more positive electrical interconnection and a reliable mechanical grip between the wire and the clamping device.

From the foregoing, it will be appreciated that there has been provided in accordance with the present invention a practical and easily assembled electrical connector useful as a terminal splice or tap. In a typical so-called doublet, as illustrated in FIGS. 2 through 9 inclusive, there are seven basic parts which may be readily assembled. The four clamping devices which are identical in construction (see FIG. 8) may be dropped into their respective vertical guideways in the insulating body 20. The respective conductive straps 76, 78 are pushed longitudinally into their passages 60, 62, and the assembly is complete, in condition for shipping. There is no need to tighten down the screws 74 of the respective clamping devices 64, 66, 68 and to avoid losing screws due to vibration. The initial assembly of the screws in the respective clamping members establishes a binding action which precludes loosening until deliberately turned by the user.

The lateral dimension of the doublet connector 14 is substantially less than that which would normally be needed for the size of the par-ts involved. Despite this reduction in width, a relatively long surface leakage path is established between adjacent terminal portions of the different current paths (of diffierent circuits) through the doublet connector. The leakage path is represented by the minimum distance across the surface of the wall portion 34:: between the clamping device 64 and the adjacent clamping device 68. A long leakage path is essential in connectors to be used where the circuit voltage is significant, that is, where breakdown should be expected if there are too-short surface leakage paths. Integrally interconnected wall portions 34a, 34b, 34c and 34d thus constitute a wall dividing circuit path 68, 78, 70 from circuit path 64, 76, 66. The surface leakage path from clamping member 70 around the end 26 and along the exposed lateral surface of wall portion 34d is a long leakage path, and the same condition is established at the opposite end of the conductor. Wall 32 underneath connecting strips 76 and 78- extend integrally from separating wall 34a, 34b, 34c, 34d. This blocks any downwflard surface leakage paths between the two circuit paths provided by the doubletconnector and between each such circuit path and the mounting rail 18. The latter is normally grounded and presumably operates at a considerable voltage difference from the voltages of connector strips 76 and 78 in usual installations.

Long surface leakage paths between the next-adjoining current paths of adjoining connectors (FIG. 1) for the minimum surface path from connector clamp 66 to connector clamp 70' extends along the exposed lateral surface of wall portion 30b. The separating wall that divides adjoining current paths through side-by-side abutting doublet connectors is one that includes discontinuous wall portions 28b and 30b, and wall portions 28a and 30a, and such discontinuities do not interfere with its effect as a separating barrier.

Each clamping member and its screw, while of metal, does not form any significant part of the current-carrying structure. As may be observed in FIGS. 6 and 9, the clamps serve for mechanically driving the inserted conductors, usually wires, against the conducting strips 76 and 78. The clamps slide vertically in guideways previously described, and they are captive in the insulating block because the treminal parts of conducting strips 76 and 78 overlie the bottom walls of the clamping members. Further (see FIG. the end openings through which wires are to be inserted involve formations that largely shield the edges of the clamping members. By virute of this construction, there is little chance for separate strands of an inserted stranded wire finding their way around the outside of the side Walls 72b and 72c of a clamping member. This is true both for clamping members 64 and 70 that are disposed at the ends 24 and 26 of the molded block and for clamping members 66 and 68 at recessed positions. In this connection, not only does wall portion 34d constitute a guiding surface for a wire to be inserted into clamping member 66, but wall portion 30b similarly forms a guiding surface for the wire to be inserted. This is because both Wall portions 34d and 30b have confronting exposed lateral surfaces that are approximately aligned with the inside surfaces of clamping device 66. The clamping members, as viewed in end projection, are closer together than the thickness of the insulating wall portions that flank such connecting devices. This feature promotes facility of inserting a Wire into a recessed clamping device, and it also leads to a closer side-by-side distribution of current paths provided by the assembly of connectors than would obtain otherwise. This arrangement is achieved without undue reduction in insulating wall thickness because, as the clamping members are viewed in lateral projection, there is no overlap. For example, wall portion 34b is of adequate thickness despite the extreme closeness of clamping members 66 and 70 as viewed in end projection.

As a further feature of the present invention, provision is tnade between adjacent connectors along the mounting rail 18 to resist the twisting torque developed due to tightening of the respective clamping screws 74 of the clamping devices, i.e., clamping devices 64, 66, 68 and 70 of the connector 14 and the corresponding clamping devices of the adjacent connector 12. To this end, and as seen in FIG. 1, one or more of the portions of the wall 28 (i.e., portions 28a, 28b) of the connector 14 interengage with corresponding and complementary recesses or seats formed in the adjacent outer wall of another connector 12, which is a duplicate of connector 14. In similar fashion, the adjacent outer confronting lateral faces of the single connector and of the triple connector 16 may be provided with projections, which have been generally designated by the reference numerals 1 0a and 16a, which engage with corresponding projections on the adjacent Walls of the connectors 12 and 14, respectively, to resist the force developed during tightening of the various clamping screws. For this purpose, the lateral surfaces of the adjacent connectors include surfaces that are generally transverse to channel 18; and the lateral surfaces also include shoulders 80 (FIG. 2) which, here, extend along the centerline of the channel 18. It will be appreciated that the configuration of the respective adjacent abutting walls may vary, depending upon the design of the respective insulating bodies, yet a design may be selected to establish the desired interengaging means for transmitting the screw-tightening torque directly imposed on one connector to the adjacent connectors. This avoids imposing the entire screW-tightening torque on the mounting formations 40, 42 of only one block 20. The transmitted torque to mounting formations of other blocks is applied at greater distances from the screw being tightened, so as to be more eifective in providing reaction to such torque, with much reduced stress on any one mounting formation 40, 42.

' Reference will now be made to FIG. 10 which'shows a modified screw-type clamping device. device is substantially identical in construction to the clamping device 68 and accordingly like parts will not be described, but will be identified by corresponding reference characters of a series. In this embodiment, the base wall 172a is formed with an integral depending skirt 172k which is in substantial copolanar relation to the wire-inserting opening 162a and is arranged to block access to the space between the base wall 172a and the bottom wall 132 of the insulating body 120. This provision facilitates proper insertion of wires into the connectors.

Referring now specificially to FIGS. 11 and 12, there is shown a modification demonstrating further features of the present invention. In the embodiment illustrated in FIGS. 2 to 9, inclusive, the respective guideways of the first and second pairs are disposed in longitudinal alignment and each has substantially the same transverse orientation on the insulating body 2t) (see, for example, FIG. 2). In this embodiment, one clamp-receiving cavity or guideway of each pair is disposed at an acute angle to a longitudinal medial plane of the body. In endwise projection, the angled clamping devices overlap each other and the non-angled clamping members of the adjacent current path provided by the connector. Since the structure of the electrical connector shown in FIGS. 11 and 12 is substantially identical to that disclosed in the previous embodiments, except for the rearrangement described above, corresponding reference numerals as part of a 200 series will be applied to this embodiment. Specificially, the insulating body 220 is provided with a first pair of vetrically extending guideways 244, 246 and a second pair of vertically extending guideways 248, 250. The guideways respectively receive clamping devices 264, 266, 268 and 270 of the type previously described. However, in this embodiment, the guideways 266, 268 of the first and second pairs respectively are disposed in substantial alignment with each other and extend along a line at an acute angle to the longitudinal medial plane of the body 220, while the guideways 264, 270 of the first and second pairs respectively are disposed on opposite sides of the medial palne and have substantially the same transverse orientation on the body 220. Such orientation is helpful in further diminishing the width of the respective insulating bodies, as measured along the length of the associated mounting rail. With this particular configuration, the respective connecting straps are modified such that they may be inserted through the top wall into corresponding sinuous channels formed between the respective vertical guideways 244, 246 and 248, 250. The configuration of one of the conductor bridging straps, which is designated by the reference numeral 278 and is the counterpart of strap 78 is illustrated in FIG. 12. The assembly requires the preliminary sub-assembly of the associated clamping devices 268, 270 with the strap 278, as indicated by the directional arrows in FIG. 12, followed by the final assembly of the three parts 268, 270 and 278 into the corresponding guideways 268, 270 and the interconnecting channel. Appropriate tangs or detents (not shown) will resist any tendency of straps 276 and 278 to be lifted out of the insulating block. In any event, once wires are inserted through openings in the insulating block (as described in connection with FIGS. 2-9), the Wires will prevent lifting of the metal parts of the connector out of the recesses. Because of the wide dimension of connecting strap 278 extending vertically, between the clamping devices, there is a reduction in overall Width of the double connector without sacrifice to the cross-section of the connecting strap and, therefore, Without loss of currentcarrying capacity of each current path provided by the connector.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some in- This clamping 9 stances some features of the invention will be employed Without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. A terminal block including one-piece block of insulation and a pair of individual circuit connecting assemblies contained therein, each said assembly including an elongated essentially straight and flat metal strip and a pair of screw-type wire clamps at the opposite ends of said strip, said metal strips having their broad surfaces parallel to the top of the block and being disposed sideby-side and being longitudinally staggered so that one end of each said metal strip and the clamp thereon is laterally adjacent to an intermediate portion of the companion strip, each said wire clamp including a rectangular frame slidably received in a cavity in said block of insulation with a corresponding end of one of said metal strips disposed above the bottom of the frame and said wire clamp including a screw that is threaded through the top of the frame and engageable with a broad surface of one of said strips for clamping an inserted wire between said bottom of the frame and said one end of said one strip, said block including an integral wall of insulation interposed between said connecting assemblies, the extent of said longitudinal staggering being such that the clamps, when viewed in projection transverse of said elongated metal strips, do not overlap each other, and said circuit connecting assemblies being staggered transversely so that said clamps when viewed or projected endwise relative to said elongated metal strips, appear closer together than the thickness of said insulating wall.

2. A terminal block, including a body of insulation and a pair of individual circuit connecting assemblies, each assembly including an elongated conductor and first and second screw-type wire clamps at the respective ends of the conductor, said conductors being longitudinally staggered so that one end of each conductor and said first wire clamp thereon are laterally adjacent to an intermediate portion of the other of said conductors, said body of insulation including an integral Wall of insulation interposed between and separating said circuit connecting assemblies, said Wall having portions extending laterally along one side of each of said second clamps, the exposed surface of each said wall portion opposite said second clamp of one of said connecting assemblies being substantially aligned with the inside surface of said first wire clamp of the other of said connecting assemblies.

3. An electrical terminal block for separately interconnecting at least two conductor pairs, including an elongated insulating body, means defining first and second pairs of cavities in said body, each cavity having an entry end in the top of said body and a wire-receiving passage that opens toward the nearest end of said insulating body, one of said first pair of cavities being disposed adjacent one end of said body and the other of said first pair of cavities being spaced inwardly from the other end of said body, one of said second pair of cavities being spaced from said one end of said body and disposed inwardly and laterally of said one of said first pair of cavities and the other of said second pair of cavities being disposed adjacent said other end of said body and disposed outwardly and laterally of said other of first pair of cavities, and first and second pairs of conductor clamps in said first and second pairs of cavities, respectively, each of said clamps including a metal frame slidably guided in a respective one of said cavities and having walls at the top, bottom and sides thereof defining a wire-receiving opening aligned with the wire-reeciving passage of said cavity, and each said clamp having an operating screw through the top of the frame and accessible at the entry end of its cavity, and a pair of bridging conductors fixed in said insulating body, each said conductor having end portions extending above the respective bottom walls and below the respective screws of respective clamps.

4. A terminal block including an insulating body having an upstanding guideway open at the top and having a lateral relatively large wire-receiving passage and said body having a portion forming a bottom wall of the guideway, and said terminal block including a clamping member having a base wall, upstanding first and second side walls projecting from said base wall and disposed adjacent the sides of said guideway and a stop wall, a contact member mounted on said insulating body and extending be tween said first and second side walls and in spaced relation to said base wall and cooperating therewith to define a socket having an open end adapted to receive a multi-strand conductor, a screw threaded in said top wall and bearing against said contact member, said base wall moving relative to said contact member in response to operation of said screw to decrease the cross-section of said socket for releasably securing an inserted conductor therein, means integral with said insulating body and bounding said open end of said socket and projecting inwardly relative to said side walls of said clamping memher to preclude accidental insertion of strands of said conductor between said clamping member and the adjacent sides of said guideway, and a skirt depending from said base wall and arranged to block the otherwise open space intermediate said base Wall and said bottom wall of said guideway when said base wall is spaced substantially from the bottom wall of the cavity to preclude accidental insertion of strands of a conductor into said space.

5. In combination, a mounting rail and a series of terminal blocks disposed thereon, said rail and said terminal blocks having complementary formations adapted for plug-in assembly of the blocks to the rail by movement along a line from the top to the bottom of each block and for securing the blocks to the rail, each terminal block including at least one connector that includes a clamping screw that must be tightened to secure an inserted wire in place, successive ones of the series of terminal blocks having confronting surfaces transverse to said mounting rail and said successive blocks having abutting shoulders in non-interfering relationship from top to bottom of said blocks and substantially perpendicular to a line across said mounting rail for resisting transmission of screw-operating torque from a screw to the rail by transmitting such torque from one terminal block via said shoulders to the next adjacent terminal block of the series of blocks on the rail.

6. A terminal block including a block of insulation, an elongated conductor in said block having means at each end thereof for making respective connections to and thus interconnecting two circuit elements, said means at one end of the elongated conductor including a clamping frame about one end of said conductor, said frame having a top wall and a screw extending through said top wall and against one side of the conductor for drawing the bottom of said frame toward the opposite side of said conductor, thereby to grip an inserted circuit element, said body of insulation having an elongated fourwalled cavity transverse to said conductor slidably containing said clamping frame and having an entry in the top of the block for inserting said clamping frame prior to insertion of the conductor into the block and for operating access to said screw, and said block having a passage for endwise insertion of said elongated conductor into said block and into said clamping frame, and means securing said elongated conductor to said block in its inserted position.

7. A terminal block in accordance with claim 6 wherein said clamping frame includes a relatively wide wall confronting said elongated conductor and wherein said frame has relatively thin and wide parallel side walls in sliding contact laterally and edgewise with the walls of said cavity, said block having a passage aligned with the inside surfaces of said frame side walls for admitting and guiding an inserted circuit element into said frame.

8. A terminal block including a block of insulation, an elongated metal strip having means at each end thereof for making respective connections to and thus interconnecting two circuit elements, said means at one end of the metal strip including a rectangular clamp having an opening that receives said metal strip, the clamp having relatively thin and wide top, bottom and mutually confronting side walls whose wide surfaces define said opening, the top wall having a screw threaded therethrough, the top and bottom walls confronting opposite faces of said metal strip, said side walls being substantially flat and having substantially parallel edges, said body of insulation having an elongated cavity whose lateral surfaces engage and guide said side walls and said parallel edges, said body of insulation completely and continuously surrounding the portion of said clamp from said metal strip to and above said top wall, said body of insulation having a passage for endwise insertion of said elongated metal strip transverse to said elongated cavity, said cavity having an entry in the top of the block for admitting said clamp prior to full insertion of said metal strip and said screw being accessible for operation via said entry end of the cavity and bearing against one side of said metal strip for drawing the bottom wall of the clamp against the opposite side of said metal strip, said block of insulation having a wire-receiving opening aligned with the space between said bottom wall and said strip.

9. A terminal block, including a block of insulation, an elongated conductor in said block, said block having a passage for admitting said conductor lengthwise end said conductor and said block having interengaging means fixing the conductor in its inserted position in the block, said body having an elongated cavity transverse of said passage and into which said conductor extends transversely, and said cavity having an entry end in the top of said body, said body having a lateral Wire-receiving passage entering said cavity below said conductor, and a clamp having top, bottom and side walls proportioned for entry into said body through said entry end of said cavity and slidable in and completely surrounded by said cavity with the top and bottom wall of the clamp disposed at opposite sides of said conductor, and a screw threaded through said top wall and bearing against said conductor to draw said bottom wall toward said conductor so that a wire inserted into said wire-receiving passage and between said conductor and said bottom wall will be clamped against said conductor, said screw being accessible for operation via said entry end of said cavity.

10. In combination, a mounting rail, at least a pair of terminal blocks, cooperating formations on said mounting rail and on each of said terminal blocks adapted for plug-in assembly of the blocks to the rail by plugging-in motion of each block along a line from its top to its bottom and for detachably mounting said terminal blocks on said mounting rail in side-by-side abutting relation, at least one wire-receiving clamp in each of said terminal blocks. and each clamp including a screw operable to cause the clamp to grip an inserted conductor, and interlocking formations on abutting portions, respectively, of said terminal blocks in non-interfering relationship in the direction from top to bottom of said blocks and said interlocking formations having engaging surfaces extending substantially perpendicular to a line across said mounting rail for resisting twisting torque developed incident to operation of each said clamping screw.

References Cited by the Examiner UNITED STATES PATENTS 985,821 3/1911 Manson 339-219 1,926,927 9/ 1933 Woertz 3171 18 2,397,102 3/1946 Graham 339198 2,687,517 8/1954 Despard 339--263 2,716,434 8/1955 Crowther 15121 X 2,958,068 10/ 1960 Lipinski 339272 X 2,983,897 5/1961 Blanchet 339198 3,018,464 1/1962 Mrenna et al 339198 FOREIGN PATENTS 1,151,655 8/1957 France. 1,100,123 2/1961 Germany. 1,106,829 5/1961 Germany. 920,169 3/ 1963 Great Britain.

223,624 1/ 1942 Switzerland.

JOSEPH D. SEERS, Primary Examiner.

ALBERT H. KAMP-E, Examiner.

a A. S. TRASK, Assistant Examiner. 

5. IN COMBINATION, A MOUNTING RAIL AND A SERIES OF TERMINAL BLOCKS DISPOSED THEREON, SAID RAIL AND SAID TERMINAL BLOCKS HAVING COMPLEMENTARY FORMATIONS ADAPTED FOR PLUG-IN ASSEMBLY OF THE BLOCKS TO THE RAIL BY MOVEMENT ALONG A LINE FROM THE TOP TO THE BOTTOM OF EACH BLOCK AND FOR SECURING THE BLOCKS TO THE RAIL, EACH TERMINAL BLOCK INCLUDING AT LEAST ONE CONNECTOR THAT INCLUDES A CLAMPING SCEW THAT MUST BE TIGHTENED TO SECURE AN INSERTED WIRE IN PLACE, SUCCESSIVE ONES OF THE SERIES OF TERMINAL BLOCKS HAVING CONFRONTING SURFACES TRANSVERSE TO SAID MOUNTING RAIL AND SAID SUCCESSIVE BLOCKS HAVING ABUTTING SHOULDERS IN NON-INTERFERING RELATIONSHIP FROM TOP TO BOTTOM OF SAID BLOCKS AND SUBSTANTIALLY PERPENDICULAR TO A LINE ACROSS SAID MOUNTING RAIL FOR RESISTING TRANSMISSION OF SCREW-OPERATING TORQUE FROM A SCREW TO THE RAIL BY TRANSMITTING SUCH TORQUE FROM ONE TERMINAL BLOCK VIA SAID SHOULDERS TO THE NEXT ADJACENT TERMINAL BLOCK OF THE SERIES OF BLOCKS ON THE RAIL. 